As a disk brake provided in a vehicle, e.g. an automobile, there has been generally known a disk brake which comprises a mounting member secured to a non-rotating part of a vehicle, a pair of friction pads supported by the mounting member and pressed against both sides, respectively, of a disk in response to the supply of hydraulic pressure to a caliper, and an urging spring (what is called an anti-rattle spring) provided between each of the friction pads and the mounting member to urge the associated friction pad toward the exit side of the rotational direction (circumferential direction) of the disk when the vehicle runs forward, and in which the urging spring is configured to have a function of detecting a wear condition of the friction pad (for example, see Patent Literature 1).